It was found that c-Met (mesenchymal-epithelial transition factor) is a receptor on a cell surface and a cancer gene (oncogene) of a receptor tyrosine kinase family, and is configured of alpha (a) sub-unit only consisting of 50 kD of extracellular domains, and beta (β) sub-unit consisting a total of 145 kD of tyrosine motif related with extracellular, cellular membrane permeation, tyrosine kinase domain, and phosphorylation (Dean et al., Nature, 4; 318(6044):385, 1985; Park et al., PNAS, 84(18):6379, 1987, Maggiora et al., J. Cell Physiol., 173:183, 1997). It has been reported that expression of inappropriate c-Met or HGF is related with various types of malignant tumors, and when it is over-expressed, prognosis is not good (www.vai.org/met, Eder et al., Clin. Cancer Res., 15:2207, 2009).
c-Met responds to HGF and stimulates various signal transduction pathways through phosphorylation of c-Met to promote transformation, that is, to promote mitogenesis of tumor cells and blood vessel cells and motility of cells, inhibits cell death, and induces angiogenesis, and invasion and metastasis to an extracellular matrix (ECM), etc. (Jeffers et al., J. Mol. Med., 74:505, 1996; Amicone et al., EMBO J., 16:495, 1997; Matsumoto and Nakamura, Biochem. Biophys. Res. Comm., 239:639, 1997; Corps et al., Int. J. Cancer, 73:151, 1997). In particular, it has been reported that c-Met and HGF are simultaneously over-expressed in various cancer tissues and cells such as glioma (Koochekpour et al., Cancer Res., 57:5391, 1997), breast cancer (Nagy et al., Surg. Oncol., 5:15, 1996; Tuck et al., Am. J. Pathol., 148:225, 1996), pancreatic cancer (Ebert et al., Cancer Res., 54:5775, 1994), pleural mesothelioma (Tolpay et al., J. Cancer Res. Clin. Oncol., 124:291, 1998); (Klominek et al. Intl. J. Cancer, 76: 240, 1998), etc. However, cases in which development into cancer progresses by over-expression of c-Met regardless of HGF, have been frequently observed. For example, there are liver cancer (hepatocellular carcinoma, Suzuki et al., Hepatology, 20 (5): 1231, 1996), gastric cancer (Taniguchi et al., Cancer, 82:2112-2122 (1998)), lung cancer (Harvey et al., J. Pathol, 180: 389, 1996), kidney cancer (Natali et al., Intl. J. Cancer, 69:212, 1996), ovarian cancer (Nagy et al, J. Surg. Oncol, 60:95, 1995), colorectal cancer (Hiscox et al., Cancer Invest., 15:513, 1997), etc., as good examples. When c-Met is activated or over-expressed, transformation is promoted as described above, such that various methods of inhibiting activation of c-Met have been developed as promising anti-cancer therapeutic strategy. As examples thereof, there are low molecular weight compounds which are designed to interfere with binding of ATP (adenosine triphosphate) to c-Met. The low molecular weight compounds include K252a (Fermentek Biotechnology), SU11274 (Sugen), PHA-665752 (Pfiza), etc., (Morotti et al., Oncogene, 21(32):4885, 2002; Berthou et al., Oncogene, 23(31):5387, 2004; Pfizer, Christensen et al., Cancer Res., 63(21):7345, 2003), and these examples were designed to interfere with phosphorylation of c-Met, such that downstream proteins of signal transfer are not activated. However, the low molecular weight compounds have a disadvantage in that they are not capable of specifically inhibiting the phosphorylation by c-Met.
In addition, as a second method of neutralizing the signaling transfer mechanism of HGF/c-Met, there is a method of inhibiting the binding of c-Met and HGF which is a ligand of c-Met. The method of inhibiting the binding of c-Met and HGF includes a method of using lost HGF fragments (Matsumoto & Nakamura, Cancer Sci., 94(4):321, 2003), antibodies neutralizing HGF (Cao et al., PNAS., 98(13):7443, 2001; Kim et al., Clin. Cancer Res., 12:1292, 2006; Burgess et al., Cancer Res., 66(3):1721, 2006), or HGF precursors (pro-HGF, Mazzone et al., J. Clin. Invest., 114(10):1418, 2004) that do not activate c-Met but are bound to c-Met with stronger affinity than the original HGF. Further, peptide sequences capable of inhibiting activity of c-Met are selected by using a phage display method and panning technique, such that corresponding peptides are used to prevent activation of c-Met (Kim et al., Biochem Biophys Res Commun., 354: 115, 2007). The selected peptides are applied to molecular imaging for searching in vivo tissue or organ in which c-Met is over-expressed (Cao et al., Clin. Cancer Res., 13(20); 6049, 2007). The selected peptides have limitation in that HGF-dependent c-Met activation is only inhibited, but anti-cancer effects are actually shown in vitro or in vivo, such that it is thought that the selected peptides are effectively used through applications such as combining with existing chemotherapy, etc. In addition, gefitinib and erlotinib which are epidermal growth factor receptors (EGFR) kinase inhibitors are used as an effective cancer therapeutic agent, but frequently have drug resistance, and the reason thereof has been reported to be an intense amplification of c-Met receptor (Engelman et al., Science, 316(5827):1039, 2007), and accordingly, it is expected that when c-Met inhibitors are merge-treated, anti-cancer effects are amplified.
Further, it is well known that c-Met is activated by HGF to contribute to angiogenesis by itself, and stimulates angiogenesis throughout interaction with VEGFR-2 which is the major receptor of angiogenesis. Here, it could be observed that when inhibition is achieved by simultaneously targeting c-Met and VEGFR-2, tumor growth is synergistically inhibited in a human xenograft model (Zhang et al., IDrugs, 13:112, 2010).
It is known that dysregulation between HGF and c-Met and over-expression of c-Met play an important role in progression of metastatic cancer, and accordingly, antibody for c-Met has been largely developed as an antagonist in anti-cancer agents.
Therefore, the present inventors made an effort to develop a c-Met human antibody capable of specifically binding to c-Met with high affinity and consisting of human-derived sequences to have a low immune response-induced potential upon in vivo administration, and as a result, separated a fully human antibody bound to c-Met with high affinity and specificity from single-chain Fv(ScFv) phage library by using a phage display method, and completed the present disclosure.